The present invention relates to a high throughput biological heart rate monitor that is molecularly determined.
Throughout this application, various publications are referenced to by numbers. Full citations for these publications may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to those skilled therein as of the date of the invention described and claimed herein.
The pacemaker current, If, is present in both automatic (1) and non-automatic (2–6) regions of the heart. Further, the threshold voltage of activation varies widely among cardiac regions, being least negative in the sinus node (e.g. in rabbit sinus node it is −40 mV (7)) and most negative in the ventricle (−108 mV or more negative, depending on species (5,8,9). Interestingly, the current activates at less negative voltages in the newborn ventricle (approximately −70 mV in rat (8,10)) and the diseased adult ventricle (approximately −70 mV threshold in aged hypertensive rat (11), −55 mV in failing human ventricle (12)). The molecular and cellular bases for the regional variability of activation voltages in the normal adult heart and the regulation of ventricular activation voltage by development and disease remain to be determined, but such understanding is critical to any future therapeutic application of the expressed current in myocardium. There is a need for a reliable, high-throughput, cell based assay of drugs affecting cardiac pacemaker current (If) and/or rate. Currently, only low throughput screens involving isolated tissue, intact animal or cell-culture systems exist. The isolated tissue and intact animal system are relatively expensive and can do at best 10's of data points in a day. The cell-culture systems incorporate cells that do not beat regularly and are not uniquely based on the normal cardiac pacemaker current. Although throughput is higher, it is generally in the range of 10's of points a day. In contrast, the present invention is based on the function of the normal pacemaker current and is potentially able to screen as many as 10,000 to 100,000 compounds per month.